1. Field of the Invention
The present invention relates to a side-view endoscope provided with an objective lens that observes a subject in at least one part of the outer peripheral surface of a distal end portion on a distal end side in the insertion direction of an insertion portion, and also to an endoscope apparatus.
2. Description of the Related Art
In recent years, endoscopes have been widely used in the fields of medical treatment and industry. Endoscopes enable observation inside a duct by insertion of an elongated insertion portion into the duct.
Further, an image pickup unit is provided inside a distal end portion on a distal end side in the insertion direction of an insertion portion of an endoscope, for example, an electronic endoscope. The image pickup unit includes a plurality of objective lens groups for observing inside a duct, a solid-state image pickup device such as a CCD, and a member such as an electrical board that exchanges electrical signals with the solid-state image pickup device. The electronic endoscope is arranged so that images of an observation site are picked up by the image pickup unit.
In the case of a direct-view endoscope, in general the image pickup unit is provided inside the distal end portion by first inserting the image pickup unit into a hole portion formed along the insertion direction of the insertion portion at a distal end main body portion provided in the distal end portion, and then fixing the image pickup unit with a screw or the like that is inserted towards the hole portion from the outer peripheral surface side of the distal end portion.
For example, Japanese Patent Application Laid-Open Publication No. 8-136829 discloses a configuration in which an image pickup unit is inserted into an image pickup unit mounting hole portion that is formed along the insertion direction of the insertion portion with respect to a distal end constituting member that corresponds to a distal end main body portion. Further, an objective lens frame that retains an objective lens group including the image pickup unit is fixed by a screw for fixing the image pickup unit. The screw for fixing the image pickup unit is screwed into a screw hole for fixing the image pickup unit that is penetratingly formed from the outer peripheral surface of the distal end portion to the image pickup unit mounting hole. The image pickup unit is thereby fixed inside the image pickup unit mounting hole.
Further, Japanese Patent Application Laid-Open Publication No. 2003-159215 discloses a configuration in which a flange portion that protrudes in an outer peripheral direction is formed at one part of the outer peripheral surface of a fixing ring that retains an objective lens unit including an image pickup unit, and a tapered portion that is oriented in the outer peripheral direction of the distal end portion is formed in the flange portion. When a fixing screw having a tip that is formed in a cone shape via a fixing screw hole is tightened towards the tapered portion from an outer peripheral surface of the distal end portion, the surface at the tip of the fixing screw and the surface of the tapered portion of the objective lens unit come in contact, the fixing ring moves to the rear end side in the insertion direction and contacts against one part of a distal end portion main body provided in the distal end portion. As a result, the image pickup unit is fixed in a hole portion formed along the insertion direction in the distal end portion main body.